spotify-dbus.py errors out when gnome-settings-manager is not installed, because it cannot use the 'org.gnome.SettingsDaemon.MediaKeys' dbus interface, attached patch ignores this error
Created attachment 329944 [details, diff] spotify-dbus-optional-gnome.patch
submitted patch upstream, if no-one responds 'soon' I will patch myself in the ebuild.
Merged upstream.
fixed in gnome-integration-spotify-20121119
Matthew, there was some indentation issue with your patch that broke the script (spotify wouldn't launch). My bad for merging without testing - I've submitted a fix and tagged 20121120, please update the ebuild.
Removed 20121119 and replaced with 20121120, yay tabs. Thanks for catching it.